This invention is concerned with the pressure regulation and delivery of hydraulic fluids, and particularly to agricultural applications such as for the control of crop spraying equipment. Crop control with liquid sprays is widely used, the liquid being used as the carrier of chemicals for insect control, fertilization and defoliation etc. It is the precisely adjusted delivery of liquid spray material to spray bars (not shown) which is a general object of this invention, and specifically it is the remote adjustment of a by-pass and shut-off valve for the control of said delivery.
Chemical application to crops is most often by means of spray application from vehicles traversing the fields thereof. The vehicle (not shown) usually a tractor or the like, carries or draws a supply tank of liquid chemical, and the prime mover thereof drives a positive displacement or like pump that supplies fluid under pressure to a delivery line 10. It is common practice to employ an adjustable valve V having an outlet line 11 to the spray bars, and having a by-pass line 12 returning to the supply tank or pump inlet. It is of course most practical to locate the valve V in the direct line 10-11 to the spray bars, however such an installation is invariably within the complexities of the power transmission and undercarriage of the vehicle and consequently remote and inaccessible to the person operating the vehicle from the conventional driver platform, cab and seat. As a result, pre-adjustment of the valve V has been a requirement and in reality unsatisfactory, since variation in engine speed of the vehicle will adversely affect the delivery of fluid to the spray bars, as a result of the orifice effect of the nozzles that determines the volume of spray and pressure thereof. It is therefore an object of this invention to provide a remotely adjustable control for pressure-volume by-pass and shut-off valves of the type under consideration, whereby a vehicle driver can adjust or close fluid delivery to the spray bars while driving, in order to compensate for changes in engine-pump speed of the vehicle operation, all as circumstances require according to the particular crop needs.
The by-pass valve as it is disclosed herein is an improvement over the Fluid Handling Valve which is the subject of U.S. Pat. No. 2,997,273 issued Aug. 22, 1961 to Norman P. Nilsen. Said prior art valve was not intended, at that time, to be infinitely adjustable as it was operated by a ratchet control into fully opened and closed positions so as to alternately open outlet and by-pass lines. More recently it has been the practice to alternately adjust the outlet and by-pass ports of such a valve in order to obtain precise spray volume adjusted to engine-pump speed of vehicle operation. In carrying out the adjustment, the by-pass port is gradually closed as the outlet port is gradually opened; and the said outlet port is shaped so as to increase from an initially miniscule flow volume. These are the characteristics of the by-pass valve with which this invention is concerned, for its remote control and precise determination of chemical spray delivery and/or shut-off.